*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body{
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: #5d3800;
}
.face{
  position: relative;
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background-color:#ffcd40;
  display: flex;
  justify-content: center;
  align-items: center;
}
.face::before{
  content:'';
  position: absolute;
  top:180px;
  width: 150px;
  height: 70px;
  background-color: #b57700;
  border-bottom-left-radius: 70px;
  border-bottom-right-radius: 70px;
  transition: .5s;
}

.face:hover::before{
  top:200px;
  width: 150px;
  height: 20px;
  background-color: #b57700;
  border-bottom-left-radius: 0px;
  border-bottom-right-radius: 0px;
  transition: .5s;
}
.eyes{
  position: relative;
  top: -40px;
  display: flex;;
}
.eyes .eye{
  position: relative;
  width: 80px;
  height: 80px;
  display: block;;
  background-color: #fff;
  margin: 0 15px;
  border-radius: 50%;
}
/* 通过伪元素添加瞳孔*/
.eyes .eye::before{
  content:'';
  position: absolute;
  top: 50%;
  left: 25px;
  transform: translate(-50%,-50%);
  width: 40px;
  height: 40px;
  background:#333;
  border-radius: 50%;
}
